The two-lined salamanders of the Eurycea bislineata complex are aquatic and semiaquatic plethodontids distributed throughout much of eastern North America, ranging from Quebec to the Gulf of Mexico and westward to the Mississippi River (Mittleman 1949, 1967; Sever 1989, 1999a,b,c; Petranka 1998; Soderberg et al. 2009). Despite often being locally abundant (King 1939; Crocker et al. 2007; Jakubanis et al. 2008) and easily found within their range in eastern North America, understanding the diversity and distributions of species in this complex remains one of the most vexing taxonomic challenges in the herpetology of the eastern United States. Green described E. bislineata (Green 1818) from specimens probably obtained near Princeton, New Jersey, USA (Fowler 1907), and E. cirrigera (Green 1831) from specimens obtained near New Orleans, Louisiana, USA, which he distinguished primarily on the namesake presence of the male secondary sexual characteristic of nasal cirri in the latter (Green 1831). These two names occupied the large geographic range of two-lined salamanders for nearly a century, although Smith (1877) recognized cirrigera as only a variety (equivalent to subspecies) of bislineata. Dunn (1920) followed Smith in treating bislineata and cirrigera as subspecies, and also described a third, E. b. wilderaeDunn 1920, from White Top Mountain, Virginia, USA, that he distinguished by having cirri in most males, slender habitus, long tail, light body coloration, and distinctive dorsolateral stripes that usually extended only onto the proximal half of the tail. Populations near the northern limit of the range of the E. bislineata complex in Quebec were later described as the subspecies E. b. majorTrapido and Clausen 1938, but these were synonymized with E. b. bislineata by Mittleman (1949), who in turn described E. b. rivicolaMittleman 1949 from Indiana that Sever (1972) also synonymized with E. b. bislineata.
Sever (1979) described an additional form of males called “morph A” (= “guarding” males sensu Pierson 2019; Pierson et al. 2019) from within the range of wilderae, and later from within the range of cirrigera (Sever 1989), that differed from typical (= “searching” males sensu Pierson 2019; Pierson et al. 2019) by having hypertrophied jaw musculature (i.e., enlarged heads) but lacking mental glands, enlarged premaxillary teeth, and nasal cirri during the breeding season. Sever (1979, 1989,...
